You can disable the Wi-Fi function by following these steps.
To enable the Wi-Fi function, turn off Airplane mode and change the Wi-Fi setting under Wireless devices to On.
To disable all wireless functions, turn on Airplane mode. The WIRELESS indicator light will be turned off.
The wireless function(s) whose setting is on will be enabled when you turn off Airplane mode. When any wireless function is enabled, the WIRELESS indicator light turns on.
Refer to Windows Help and Support (Opening Windows Help and Support) for more information on Airplane mode.